Phenol/Chloroform

Recently a coworker came into my lab and asked about the buffer layer from
phenol/chloroform solutions becoming alkaline over time which in
their view would necessitate immediate disposal of the reagent to prevent
ruining valuable samples. I had not heard of this before so I immediately
checked the pH of my stock and found it to be about pH 10, by a test paper. I
disposed of it and made up some new reagent, but it was also alkaline!
Does anyone know about this? Does it matter?
Mike T.